Sundance Spas ST201 manual Txframecontrol

Sundance Technology

ST201

PRELIMINARY draft 2

TXFRAMECONTROL

Class	DMA Data Structures, TFD
Base Address	Start of TFD
Address Offset	0x04
Access Mode	Read/Write
Width	32 bits

TxFrameControl contains frame control information for the TxDMA function and the transmit function.

BIT

1..0

9..2

12..10

13

14

15

16

30..17

31

BIT NAME

WordAlign

FrameId

Reserved

FcsAppendDisable

Reserved

TxIndicate

TxDMAComplete

Reserved

TxDMAIndicate

BIT DESCRIPTION

These bits determine the boundary to which transmit frame lengths are rounded up in the TxFIFO, and transmitted onto the network medium.

00:Align to dword

10:Align to word X1: Align disabled

This field can be used as a frame ID or sequence number. This value is saved with the frame in the TxFIFO, and made visible in the TxFrameId register while the frame is being transmitted. When a transmit error occurs, the driver checks TxFrameId to determine which frame experi- enced the error.

Reserved for future use. Should be set to 0.

The host system sets this bit to prevent the ST201 from appending the 4-byte FCS to the end of the current frame. In this case, the host sys- tem must supply the frame’s FCS as part of the data transferred by TxDMA to the TxFIFO. An exception exists when a transmit under run occurs; in this case a guaranteed-bad FCS will be appended to the frame by the ST201. When FcsAppendDisable is cleared, the ST201 will compute and append FCS to this transmit frame.

Reserved for future use. Should be set to 0.

The host system sets this bit to request a TxComplete interrupt upon completion of MAC transmission of this frame. If TxComplete is cleared, no interrupt of transmit completion will be given by the ST201, unless a transmit error occurs.

Indicates that the frame transfer by TxDMA is complete. The ST201 sets this bit after it has finished transferring via the TxDMA process all of the fragments specified in the TFD.

Reserved for future use. Should be set to 0.

Set if the host system desires a TxDMAComplete interrupt upon com- pletion of TxDMA of this frame. The TFC is read twice by the ST201; the first time to write the TFC to the TxFIFO before frame data transfer, and again after the TxDMA operation is complete to test TxDMAIndi- cate in order to determine whether to generate an interrupt. This allows the host system time to change TxDMAIndicate while the transfer by TxDMA is in progress.

31